Absorbent pads for absorption of body fluids such as urine, menses or blood or vaginal discharges are well known in the art, and comprise for example sanitary napkins, panty liners, as well as adult incontinence pads. These articles typically comprise a liquid pervious topsheet as wearer facing layer, a backsheet as garment facing layer and an absorbent core between topsheet and backsheet. The body fluids are acquired through the topsheet and subsequently stored in the absorbent core. The backsheet typically prevents the absorbed fluids from wetting the wearer's garment. Absorbent pads often comprise side flaps provided on the side edges of the napkin meant to be fold around the crotch edge of an undergarment during use in order to protect the undergarment from side leakages. The present invention refers to absorbent pads comprising side flaps.
The absorbent core typically comprises one or more absorbent materials. Absorbent materials can be comprised typically in fibrous or particulate form, but also unitary elements formed by absorbent materials such as absorbent foam can be used.
Absorbent materials can be selected among all absorbent materials known in the art, for example natural fibres (such as for example cellulose fibres, typically wood pulp fibres), artificial fibres (such as rayon, viscose), absorbent and superabsorbent polymers (which can be used in the form of particles or fibres or foam layer or foam particles or combination thereof). Typically the absorbent core has a layered structure and is formed by one or more layers.
Absorbent pads typically comprise an adhesive on the garment facing side of the backsheet. Such adhesive is protected by a release film which can be for example a sheet of siliconized paper. Absorbent pads are commonly marketed in folded configuration. In the most common configuration absorbent pads have two folding lines which are parallel to the transverse axis of the absorbent pad. Typically absorbent pads are folded and wrapped individually with a thin plastic film. Sometime the inner surface of the wrapper film is treated with a release agent such as silicone so that the film itself can also act as release film protecting the adhesive and releasing it when the wrapper of the absorbent pad is removed. Always sanitary napkins from The Procter & Gamble Company are currently marketed using this type or wrapper/release film.
The main purpose of such absorbent pads is clearly to absorb and retain body fluids and preventing as much as possible that such fluids escape from the article causing soiling of underwear and embarrassment of the user. The use of side flaps is well established and has allowed reducing the risk of soiling of the underwear following fluid escape from the sides of the absorbent pad.
Nevertheless, despite less frequent in absorbent pads of modern construction, fluid leakage still occurs in some cases and therefore there is a continued interest in the industry to identify solutions to solve this problem more effectively.
So far the conventional approach has been to increase the length of the side flaps and/or the amount of absorbent materials and superabsorbent polymer in the absorbent core. Both these approaches, although effective, also have some drawbacks.
When side flaps are longer, more stresses are created in the flaps. The stresses are especially high along the fold line at the edges of the wearer's panties where the flaps are bent from the body side of the panty to the underside of the panty. These stresses are caused by fitting a flap around the curved edges of a panty crotch. The stresses are magnified when a wearer sits or crouches because the edges of the panties are pulled outward against the flaps thus increasing the forces against this fold line. When the stresses become too high, the flaps may become detached from the panty and some of the benefits of the flaps may be lost. In addition, even if the stresses are not sufficient to detach the flaps, they may still be sufficient to cause the flaps to bunch longitudinally inward or to form pleats. This effectively reduces the size of the flaps and the area of the wearer's undergarments that the flaps are able to cover and could cause discomfort to the wearer. Also longer side flaps in general reduce the flexibility of the article and are more difficult to correctly fold in position around the crotch edge of the undergarment.
In addition longer flaps require the use of more material and consequently both the cost for manufacturing the absorbent article and its environmental impact are increased.
If instead a larger amount absorbent material is used uniformly within the article, the absorbent article also becomes thicker and less flexible, less comfortable as well as more expensive to manufacture.
In the present invention the problem has been inventively solved by increasing the basis weight of the SAP in a small selected zone in correspondence with the end points of the side flaps. It has been observed in fact that surprisingly it is sufficient to increase the basis weight of SAP in a small defined area of the absorbent core as explained in detail in the invention description below to obtain a significant improvement in leakage reduction.